Biomolecular identification of allergenic pollen: a new perspective for aerobiological monitoring?

BACKGROUND: Accurate and updated information on airborne pollen in specific areas can help allergic patients. Current monitoring systems are based on a morphologic identification approach, a time-consuming method that may represent a limiting factor for sampling network enhancement.
OBJECTIVE: To verify the feasibility of developing a real-time polymerase chain reaction (PCR) approach, an alternative to optical analysis, as a rapid, accurate, and automated tool for the detection and quantification of airborne allergenic pollen taxa.
METHODS: The traditional cetyl trimethyl ammonium bromide-based method was modified for DNA isolation from pollen. Taxon-specific DNA sequences were identified via bioinformatics or literature searches and were PCR amplified from the matching allergenic taxa; based on the sequences of PCR products, complementary or degenerate TaqMan probes were developed. The accuracy of the quantitative real-time PCR assay was tested on 3 plant species.
RESULTS: The setup of a modified DNA extraction protocol allowed us to achieve good-quality pollen DNA. Taxon-specific nuclear gene fragments were identified and sequenced. Designed primer pairs and probes identified selected pollen taxa, mostly at the required classification level. Pollen was properly identified even when collected on routine aerobiological tape. Preliminary quantification assays on pollen grains were successfully performed on test species and in mixes.
CONCLUSIONS: The real-time PCR approach revealed promising results in pollen identification and quantification, even when analyzing pollen mixes. Future perspectives could concern the development of multiplex real-time PCR for the simultaneous detection of different taxa in the same reaction tube and the application of high-throughput molecular methods.